feat: implement complete invoicing application with CSV import and PDF export

- Add comprehensive CSV import system with drag-and-drop upload and validation
- Create UniversalTable component with advanced filtering, searching, and batch actions
- Implement invoice management (view, edit, delete) with professional PDF export
- Add client management with full CRUD operations
- Set up authentication with NextAuth.js and email/password login
- Configure database schema with users, clients, invoices, and invoice_items tables
- Build responsive UI with shadcn/ui components and emerald branding
- Add type-safe API layer with tRPC and Zod validation
- Include proper error handling and user feedback with toast notifications
- Set up development environment with Bun, TypeScript, and Tailwind CSS

src/app/api/trpc/[trpc]/route.ts

@@ -0,0 +1,34 @@
+import { fetchRequestHandler } from "@trpc/server/adapters/fetch";
+import { type NextRequest } from "next/server";
+
+import { env } from "~/env";
+import { appRouter } from "~/server/api/root";
+import { createTRPCContext } from "~/server/api/trpc";
+
+/**
+ * This wraps the `createTRPCContext` helper and provides the required context for the tRPC API when
+ * handling a HTTP request (e.g. when you make requests from Client Components).
+ */
+const createContext = async (req: NextRequest) => {
+  return createTRPCContext({
+    headers: req.headers,
+  });
+};
+
+const handler = (req: NextRequest) =>
+  fetchRequestHandler({
+    endpoint: "/api/trpc",
+    req,
+    router: appRouter,
+    createContext: () => createContext(req),
+    onError:
+      env.NODE_ENV === "development"
+        ? ({ path, error }) => {
+            console.error(
+              `❌ tRPC failed on ${path ?? "<no-path>"}: ${error.message}`,
+            );
+          }
+        : undefined,
+  });
+
+export { handler as GET, handler as POST };